1 . Field of the Invention
The present invention relates to a vaporizer and an apparatus for vaporizing and supplying that are employed for supplying a chemical vapor deposition (CVD) apparatus used in the manufacture of a semiconductor and the like with a gaseous CVD-material.
More particularly, it pertains to a vaporizer and an apparatus for vaporizing and supplying that are employed for supplying a liquid CVD-material or a solution of a liquid CVD-material or a solid CVD-material in a solvent each at desirable concentration and flow rate in high efficiency without causing deterioration in the quality of the CVD materials.
2 . Description of the Related Arts
With regard to an insulated thin film for a semiconductor device, there are available SiO2 as a gate insulated film, Si3N4 as a capacitor insulated film and PSG (phosphorus/silicon/glass) and BPSG (boron/phosphorus/silicon/glass) as an gate interlaminar insulated film.
Gaseous CVD-materials such as SiH4, NH3 ,PH3 and B2 H6 have hitherto been used as a material for manufacturing the film material by means of a CVD apparatus.
With the progress of three dimensional devices and multi-layered wiring, a demand for flatness of the insulated films steadily increases, and thus use is made of a liquid CVD-material which is less prone to generate such defect as a void, and is capable of forming thin films of high quality. For instance, there are used tetraethoxysilicon {Si(OC2H5)4} as a starting material for SiO2 film, trimethoxy boron {B(OCH3)3}, trimethoxyphosphorus {P(OCH3)3} and the like as a CVD material for BPSG film.
In addition thereto, there has been developed a new type of thin film such as Ta2O5 film having a dielectric constant several times as high as that of SiO2 film, and use is made of pentaethoxytantalum{Ta(OC2H5)5} in liquid form as a CVD material for Ta2O5 film.
Moreover, there have been used in recent years, lead titanate zirconate (PZT) film and barium strontium titanate(BST) film each having a high dielectric constant and also a high step coverage.
In regard to the CVD material for the above-mentioned thin films, there are used Pb(DPM)2 (solid material) as a Pb source; Zr{OC(CH3)3}4 (liquid material) as a Zr source; Ti{OCH(CH3)2}4 (liquid material) as a Ti source; Ba(DPM)2 (solid material) as a Ba source; and Sr(DPM)2 (solid material) as a Sr source.
A liquid material, when being used as a CVD material, is made into a gaseous form with a vaporizer or the like, and thereafter is fed to a CVD apparatus. However, it is difficult to vaporize a liquid material at a desirable concentration and flow rate in high efficiency without deteriorating the quality thereof, since the liquid material has usually a low vapor pressure, a high viscosity and a vaporizing temperature close to a decomposing temperature. A solid material, although being capable of assuring highly pure material by being kept at a high temperature to sublime itself, makes it extremely difficult to assure sufficient supply amount in an industrial scale. Thus, in general it is dissolved in a solvent such as tetrahydofuran to make it into a liquid material so as to vaporize. However, since a solid material has a vaporizing temperature greatly different from that of a solvent, a solvent alone is more apt to vaporize by heating, thereby making it more difficult to vaporize a liquid material.
Such being the case, highly advanced technique is required for manufacturing an insulated thin film by using a material in liquid or solid form. Conversely, an insulated thin film having high quality and high purity is expectable by the use of a liquid material or solid material. Accordingly, a variety of vaporizers and apparatuses for vaporizing and supplying have been developed for the purpose of efficiently vaporizing the aforesaid material without deteriorating the quality thereof.
For instance, as a vaporizer for the purpose of vaporizing a liquid material, a vaporizer is cited which is in the form of a sphere, ellipsoid, barrel, cylinder assuming roundness at an end, cone, truncated cone or hemisphere, in the form similar to any of the foregoing or in a combined form thereof, and which is set such that a carrier gas forms a swirled flow in a vaporization vessel {refer to Japanese Patent Application Laid-Open No. 342328/1999 (Heisei-11)}.
By swirling a heated carrier gas along the internal wall surface of the vaporization vessel in the aforesaid vaporizer, a material which has been atomized with an atomizer at a CVD material feed port is entangled in the above-mentioned carrier gas and is heated in contact therewith, thus preventing to the utmost, direct heating through the internal wall surface thereof from deteriorating the quality of the material and depositing on the surface. Accordingly, the vaporizer is excellent in that it is expectable to enhance vaporization efficiency.
Nevertheless, in the case of using a CVD material in which a solid CVD-material is dissolved in an organic solvent, even the use of the vaporizer brings about such fears that the solvent alone is more prone to vaporize in the CVD material feed port, the solid CVD material is deposited during a long time of application and is stuck to the passageway of the material, and thereby exerts an evil influence on the quality of the insulated thin film and the purity thereof.
It is desirable to enhance the utilization efficiency of a CVD material which is usually expensive by supplying the material in high concentration in the case of chemical vapor deposition. However, a decrease in a feed amount of a carrier gas to be supplied accompanying the CVD material brings about such disadvantage that a solvent alone is vaporized, thus causing a solid CVD-material to be more prone to be deposited.
In such circumstances, an object of the present invention is to provide, even in the case of employing a solid CVD- material, a vaporizer and an apparatus for vaporizing and supplying which comprises the aforesaid vaporizer, which is capable of efficiently vaporizing a CVD material at a desirable concentration and flow rate without causing deposit or adhesion of the solid material in the CVD material feed port.
Other objects of the present invention will become obvious from the text of this specification hereinafter disclosed.
Under such circumstances, intensive extensive research and development were accumulated by the present inventors in order to solve the above-described problems involved in the prior arts. As a result, the following has been found. Specifically, even in the case of using a CVD material in which a solid CVD-material is dissolved in an organic solvent, it is made possible to prevent rapid heating of a solid CVD-material which is one of the causes for vaporization of an organic solvent alone and also to make deposit of the solid CVD-material less liable to adhere even if such deposit is generated, by constructing constitution material for the portion in contact with a CVD material in the CVD material feed portion by means of a corrosion resistant synthetic resin which has not only heat resistance but also heat insulating properties and characteristics of less liability to adhesion of the CVD material, and which is exemplified by fluororesin and polyimide resin in particular, and further by cooling a CVD material feed portion upon heating a vaporization chamber. Thus, the present invention has been accomplished by the foregoing findings and information.
That is to say, the present invention is related to a vaporizer which comprises a vaporization chamber for a CVD material, a CVD material feed portion for supplying the vaporization chamber with the CVD material, a vaporized gas exhaust port and a heating means for heating the vaporization chamber, characterized in that at least a portion of the CVD material feed portion in contact with the CVD material is constituted of a corrosion resistant synthetic resin.
In addition, the present invention is concerned with a vaporizer which comprises a vaporization chamber for a CVD material, a CVD material feed portion for supplying the vaporization chamber with the CVD material, a vaporized gas exhaust port and a heating means for heating the vaporization chamber, characterized in that the inside of the CVD material feed portion and the surface on the side of the vaporization chamber of the CVD material feed portion are constituted of a corrosion resistant synthetic resin, and the feed portion in contact with the outside of the vaporizer is constituted of a metal.
At the same time, the present invention pertains to an apparatus for vaporizing and supplying which comprises a cooler and a vaporizer which harbors a vaporization chamber for a CVD material, a CVD material feed portion for supplying the vaporization chamber with the CVD material, a vaporized gas exhaust port and a heating means for heating the vaporization chamber, characterized in that the inside of the CVD material feed portion of the vaporizer and the surface on the side of the vaporization chamber of the CVD material feed portion are constituted of a corrosion resistant synthetic resin; the feed portion in contact with the outside of the vaporizer is constituted of a metal; and at least a part of the metal-constituted portion of the CVD material feed portion which undergoes heat transfer from the heating means at the time of heating the vaporization chamber, is of such constitution that enables said part to be cooled with said cooler.